Due to disease or insult or other causes, the renal system may fail. In renal failure of any cause, there are several physiological derangements. The balance of water, ions (e.g., Na+, K+, Cl−, Ca2+, PO43−, Mg2+, SO42−) and the excretion of daily metabolic load of fixed hydrogen ions is no longer possible with renal failure. Further, during renal failure, toxic end products of nitrogen metabolism including, for example, urea, creatinine, uric acid, and others may accumulate in the patient's blood and tissues.
Several types of dialysis treatment have been devised (e.g., peritoneal dialysis, hemodialysis, hemofiltration, and hemodiafiltration) for the removal of toxic end products of nitrogen metabolism from blood. These types of dialysis treatment rely on diffusion of urea across a membrane and/or enzymatic degradation of urea. However, degradation of urea is problematic in that it produces toxic end products such as ammonium that must be removed and/or trapped (or treatment fluid discarded) to ensure that they are not returned to a patient. Sorbents are often employed during dialysis to bind such toxic end products. These sorbents are expensive and add bulk to a dialysis system, making them less suitable to being used in portable or wearable applications.
A need accordingly exists for improved regenerative dialysis systems that remove urea from blood to reduce or eliminate the risk that toxic end products will be present in the regenerated dialysis fluid.